= Eggleton Roche-lobe radius approximation
{c}
{title2=$R_L/a=0.49q^{2/3}/[0.6q^{2/3}+\ln(1+q^{1/3})]$}
For a circular synchronized <binary star>, this approximates the volume-equivalent <Roche lobe> radius, where $q$ is the enclosed star's <mass> divided by its companion's <mass>. It describes critical equipotential geometry; it does not give the star's radius response to <mass> loss. The primary calculation reports radius errors below about one percent across the mass-ratio range.<Approximations to the radii of Roche lobes by Peter P. Eggleton>[Printed p. 368, equation 2 and accompanying comparison]{ref}
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